TGF-Beta Induced Erk Phosphorylation of Smad Linker Region Regulates Smad Signaling
Figure 3
Erk activation requires activation of Pak2 and c-Raf.
(A) AKR-2B fibroblasts were infected at an MOI of 1∶125 with adenovirus containing either dominant-negative PAK2 (Ad-EGFPdnPAK2) or Ad-EGFP as a negative control. Cells were treated with TGF-β (2 ng/ml) for 2 h prior to lysis. Cell lysates were then probed for phospho-Erk, and phospho-c-Raf (Ser338). The phospho-Erk1/2, and the stripped/reprobed total Erk loading control blot was obtained using the lower molecular mass portion of the same blot as that for P-cRaf. The same cell lysates were analyzed on a separate blot for PAK2 to confirm expression. (B) Cell lysates were analyzed for phospho-Erk and total Erk levels, in MEF cells that contained the Pak2 gene with flanking flox sites and a MEF cell line derived from this parental line in which Cre recombinase had been used to excise the Pak2 gene, following treatment with or without TGF-β for 2 h.